Considered to be one of the worst films ever made, Santa Claus Conquers The Martians is available to post, in its entirety, on your website. You could even put the movie out in the form of a smartphone app and sell it. I don't know why you would want to inflict that kind of suffering on people, but there is little to stop you. Santa Claus Conquers The Martians is in the public domain, which means that you can do anything you want with it.

And using public domain content as the basis for mashups is a growing trend, and one that is yielding a lot of great, original content. Let's take a look at how public domain material is being re-purposed on the web and in print.

5 Killer Public Domain Mashups

1. Pride And Prejudice And Zombies. Maybe you're not feeling overly ambitious and don't want to create an entire universe based on someone else's mythology. That's fine. You can always just throw in zombies, ninjas, and sea monsters. People like it when you do that. Quirk Books had to up their print run, according to Wikipedia, from 12,000 to 60,000 because of the buzz around this re-imagining of Jane Austen's Pride And Prejudice. The book has been so successful, a major feature film is in the works as well as a graphic novel, and multiple sequels based on other classic books have already been made.

2. LOLCat Bible. The LOLCat meme, which originated on 4Chan for Caturday, has come a long way. The LOLCat Bible Translation Project is funny and is a great illustration of what you can do with public content. Both Bibles (Hebrew and New) are public domain, and with the help of the crowd, the LOLCat Bible Translation Project has successfully translated the two books into "LOLSpeak." There's even a book coming out in January.

3. Fly On Time. Everything you need to know about your flight. Alright. Not quite everything, but the weather? Will your flight be on time? Thanks to information made available through Data.gov, Flyontime.us provides airline customers with plenty of useful information to help make their flying decisions. By the way, pretty much anything the federal government (US) does is public domain (though there are some exceptions). If it's not classified, it's yours.

4. John Quincy Adams on Twitter. If you're making a list of forgettable presidents, John Quincy Adams is always a virtual lock to make it. Why? Well, let's just say he became the first ex-president to be elected to congress after his first term in office. In an effort to make John Quincy more famous, the Massachusetts Historical Society has been tweeting his diary, which is in the public domain like anything authored before the early 20th century, one line per day, at @JQAdams_MHS.

5. We Tell Stories What happens when you challenge six professional authors to re-tell public domain classics and send readers on a scavenger hunt? That's the question Penguin UK asked when it sent readers on a scavenger hunt to find clues and unlock the seventh story. But the best part, and something every book publisher should take a good look at, is the way these stories are told. Using Google Maps and other social media tools, these six stories are presented in an exciting interactive way that makes opening a book seem quaint, and wouldn't have been possible without the public domain books at the project's core.

How Can You Use Public Domain Content?

There's a myth, made popular by unimaginative people, that you're either born creative or you're not. But that's not true. It would be easy to sit here and tell you to "be creative!" but that would be a cop out. So here's what I'm going to tell you: Creativity is a skill. You want to be creative? Read a lot, write a lot, and edit more.

And when you're done, there is nothing stopping you from, say, taking The Picture Of Dorian Gray, editing it down into 140 character bursts, and tweeting it. Or if you want to re-cut Duck And Coverfeaturing Burt The Turtle or make a soundboard, go for it. It's the practice of doing this that will get you ready to produce better work of your own.

And as we move toward a more video-centric web, those public domain films and shorts can represent a potential goldmine if you can figure out how to re-purpose them successfully. Not to mention the wealth of government information available for app developers and anyone else to capitalize upon.

Everything you might ever need is right in front of you.

The above video is in the public domain

So if you're frustrated, or just getting started with social media and don't have any content of your own to start with, take a page from the mashups above and get practicing ... or get rich. You never know. Maybe the slightest change to a public domain book is all you need for that retirement in Maui.

But before you get started ...

5 Tips For Public Domain Content

All discussion in this post revolves around U.S. copyright law. This is a very subjective field as the law tends to change based on who you ask. Wikipedia is an excellent and mostly reliable resource you can use to figure out what is, and what is not, public domain.

1. Archive.org and Project Gutenberg are arguably the best known resources for public domain films and books. Both websites allows you to view or download public domain works in a variety of formats. Mashable has a great list of resources here that you can use to find public domain work as well.

2. If you're going to post public domain material, add a comment in the footer of your blog that says the works posted are public domain, but should they not be for any reason, you will remove it. This will help keep you out of trouble if any item moves out of the public domain in the future.

3. Just because something is public domain, it doesn't mean that related works are also necessarily public domain. The old Fleischer Superman cartoons from the 40s are public domain, for example, but that doesn't mean all of Superman is in public domain as well. So make sure to double check what elements of a public domain work can be used. The Wikipedia page for each item usually indicates its legal status.

4. If you modify a public domain work, you own the copyright to the modified work. The best example of this is Thor. Thor is public domain, but Marvel owns the copyright to their version of Thor, so your Thor can't speak Old English and smack around Dr. Doom.

5. There are other free, but non-public domain resources that you can utilize in your mashups (such as Creative Commons-licensed Flickr photos), but always make sure you are crediting them properly!

Have you made any awesome public domain mashups of your own, or do know of any great ones I left off the list? Tell us about them in the comments section below!

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